This invention relates to daytime running lights for motor vehicles. More particularly, it is concerned with such systems which utilize conventional headlights to provide reduced intensity daytime running light illumination.
Headlight daytime running light systems are known which have a voltage dropping device selectably coupled in series with the headlamps to reduce the voltage thereacross the headlamps, thereby reducing the light output thereof. Such an arrangement wastes significant power through heat dissipation and requires relatively costly devices capable of such dissipation capacities.
Other headlight daytime running light systems utilize pulse width modulation control of the current through the headlight filaments to reduce the average power therethrough and light output thereof. However, rapid power level current switching through the large circuit loops of the vehicle wiring generates significant levels of undesirable electromagnetic noise. Addressing such shortfalls adds considerable expense to such a system.
Yet other systems are known which effectuate a series connection of the vehicle headlamps to drop substantially one-half the system voltage across each headlamp to thereby reduce light output. Such a system is inflexible in the control of the light output, which control may be desirable based upon differing international requirements.